Display device



Oct. 22, 1968 F. J. SALGO 3,407,331

DISPLAY DEVICE Filed April 7.

2 Sheets-Sheet 1 F/ONC/J J Ja(yo INVENTOR.

ATTORNEY Oct. 22, 1968 Filed April 7. 1966 F. .1. SALGO 3,407,331

DISPLAY DEVICE 2 Sheets-Sheet 2 Franc/J J Ja/ya INVENTOR.

ATTORNEY United States Patent 3,407,331 DISPLAY DEVICE Francis J. Salgo, Garland, Tex., assignor to General Electrodynamics Corporation, Garland, Tex., a corporation of Texas Continuation-impart of application Ser. No. 490,516,

Sept. 27, 1965. This application Apr. 7, 1966, Ser.

13 Claims. (Cl. 31521) ABSTRACT OF THE DISCLOSURE A display device comprising a tube having a luminous screen positioned for impingement by electrons to display selected characters or symbols, and including a barrier in the path of the electrons having portions adapted to be biased negative with respect to the electron beam and having other portions adapted to be biased positive with respect to the electron beam so that the electrons flow to the target in a desired pattern.

Cross-reference to related application This application is a continuation-in-part of my copending application Ser. No. 490,516, filed Sept. 27, 1965.

Summary of the invention In the electronic data processing and telemetering arts, it is becoming increasingly important to provide visual readout display systems with instantaneous access time which are simpler and more compact, and which can display any desired character in the same display area.

Display devices of the visual readout type, wherein selected characters or symbols may be displayed in the same display area, are known in the prior art, and these devices vary from edge lighted stacked symbol bearing Lucite plates to conventional monogram designs of selectively lighted Lucite rods, electroluminescent coated characters and glow tube displays. The deficiencies of the prior art devices are complexity of construction and assembly, relatively short life, and lack of reliability or ruggedness. This invention provides a display device construction which overcomes the deficiencies of the prior known display devices.

This invention provides a display producing device for displaying selected symbols in a common display area, wherein all symbols are displayed by excitation of a luminous phosphor which is applied to a face plate to form a luminescent screen. Means are provided for di recting an electron beam towards the luminescent screen in such a way as to form a flood of electrons moving toward the screen. Intermediate the electron source and the screen there is provided a barrier which comprises a plurality of separate conducting layers having aligned perforations through which electrons may pass to impinge on the screen. Each conducting layer is configured to form a symbol, and a background which is electrically separated from the symbol configuration. Means are provided for selectively biasing the symbols and the backgrounds to allow passage of electrons through the barrier to the screen in a pattern such as to energize the screen to display a desired symbol.

The symbols or characters which are displayed may be in the nature of numerical digits, or may be letters of the English alphabet or other alphabets, or may be special characters and symbols.

It is an object of this invention to form a visual readout unit or display device wherein selected symbols may be displayed in a single area, and wherein the symbols are formed by selectively allowing electrons to pass ice through a barrier to energize a luminescent screen in a desired pattern.

It is also an object of the invention to provide a display device which is simple in construction, with no moving parts, and which is compact and rugged and has long life.

A further object of the invention is to provide a display producing device which is capable of displaying a large variety of symbols in a single plane.

According to the present invention means are also provided to display such symbols or characters in various colors. It is an object of the invention to provide such means wherein two or more colors of symbols may be displayed on the same display device.

According to the invention the display of two or more colors on the same display device is accomplished by utilization of two or more luminous phosphors on the face plate of the display device, the phosphors being distributed separately over the face plate in such a way that impingement of the electrons can be selectively cut off from one or more of the phosphors in order to cause electron impingement to be limited to the phosphor which will respond with the desired color.

Other objects and advantages of the invention will be more apparent upon consideration of the following description and the accompanying drawings which disclose, by way of example, the principles of the invention and the best mode which has heretofore been contemplated of applying these principles in carrying out the invention.

Brief description of the drawing In the drawings:

FIGURE 1 is a longitudinal sectional view of a preferred embodiment of the invention shown partially schematically;

FIGURE 2 is a view of a portion of a fluorescent target prepared for use in the structure of this invention;

FIGURE 3 is a fragmentary view of a screen prepared for use in the structure of this invention;

FIGURE 4 is an exploded view of a typical stack of laminations utilized in a preferred embodiment of the barrier of the invention, and shown schematically with electrical connections thereto;

FIGURE 5 is an enlarged cross-sectional view of a portion of the laminated barrier illustrated in FIGURE 4', and

FIGURE 6 is a front view of a face plate of a display device according to this invention showing a display of a symbol thereon.

Description of the preferred embodiments Referring to FIGURE 1 of the drawings, the embodiment of the tube therein shown has a cylindrical glass envelope 10 with an electron gun having a cathode 14 adjacent one end of the envelope, constructed and arranged, together with other elements, to generate and project an electron beam 15 toward the other end of the tube. Collimating means 17 are provided to create a flood of substantially parallel flow electrons directed toward the opposite end of the tube. It should be realized that the foregoing construction is by way of exemplification only and details well known in the art have not been included. Constructions of this type and other types providing additional features with greater control and complex utilization of electron-optical elements as are well known in the art may be utilized.

The opposite end of the tube is closed by a face plate 12 which has applied to its inner surface a luminescent layer 13 comprising two or more luminous phosphors which have different color response upon energization by electrons. In the embodiment shown the different luminous phosphors are shown (see FIGURE 2) as alternate strips of red and green phosphors. However, this form is shown as an example only, and it is anticipated that many other arrangements of the red and green phosphors or of other colors of phosphors or of more than two phosphors may be utilized to more satisfactorily accomplish the objects of this invention. Also, in the drawing the red and green strips of phosphor are shown much wider than would normally be the case. In the usual display device, say for example, to form a symbol of about one inch maximum dimension, the phosphor elements would preferably have a maximum width of about 0.030 inch and spaces between adjacent phosphor elements of the same color would preferably be no more than about 0.030 inch in width. In many instances, smaller spacings andwidths may be preferred and spacings and widths no greater than about 0.003 inch might be found satisfactory in many cases.

Also, in the drawing the thickness of the phosphor layer is greatly exaggerated for clarity.

A screen 16 is positioned closely adjacent but separated from the fluorescent target 13. The function of screen 16 is to direct electrons to the desired color of phosphor. As shown in FIGURE 3, the screen 16 comprises a thin perforated element having a plurality of conductive areas comprising, in the embodiment shown, alternate conductive strips 18 and 20 which are arranged in a pattern or configuration corresponding to the pattern in which the phosphors are laid onto the fluorescent target. Perforations 22 extend through the screen and are preferably lined with conducting material, the screen itself being preferably an insulating material, although it is only necessary that all strips 18 are insulated from all strips 20.

In the embodiment shown, alternate conducting strips 18 on the screen 16 are all connected in conductive groups to a conductor 17 and alternate conducting strips 20 are all connected in conductive groups to a conductor 19. Conductors 17 and 19 are in turn connected to a switching apparatus (not shown) suitable for applying either a positive or negative voltage, as hereinafter defined, as is desired to the alternate strips.

As seen in FIGURE 1, the screen 16 is positioned in front of the fluorescent target with a line of perforations 22 overlying each phosphor strip on the target.

Also positioned within the tube and in between the screen 16 and the electron gun is a perforated barrier 21 which comprises, as is better shown in FIGURE 4, a plurality of alternate insulating and conducting layers. The barrier is preferably spaced away from the screen 16 a distance sufficient to allow electrons passing from the perforations of the barrier to converge to desired ones of the perforations in the screen.

In the preferred embodiment shown, the conducting layers of the carrier 21 are formed by conductive coatings 23 applied to thin insulating sheets 25. The insulating sheets 25 may, for example, comprise very thin perforated plates or disks which may be circular or rectangular or any desired geometric configuration. Such disks, for example, may be similar to those marketed under the trademark Photo-Form by the Corning Glass Company of Corning, N.Y. Such a disk has approximately 200 perforations to the inch or more, and is constructed of self-supporting glass. Other disks having fewer perforations, for example, about perforations to the inch or less, also provide good results under certain circumstances. The disks preferably used are very thin and may be as thin as 0.0005 inch or as thick as 0.003 inch or more. In a preferred embodiment, the thickness of the disk may be such that the barrier thickness is in the order of the perforation diameter. In some embodiments of the invention, much thicker insulating sheets may be used and still obtain the benefits of the invention.

In preparing the glass disks for use in one embodiment of the structure of this invention, an electrically conductive coating is applied to one side of the disk, as is done,

for example, in the structure described in US. Patent No. 3,047,768 to McNaney. This conductive layer may be of the type known by the trademark NESA, and is applied by evaporation by means well known in the art. The conductive coating is preferably applied in such a manner that the conductive material extends part way down into the perforations on the perforated disks in the manner shown in FIGURE 5. Of course, it is necessary that the conductive material not extend all the way through the perforations to contact the conductive coating on the next adjacent sheet in order that there be no shorting out between adjacent conductive layers.

Following the deposition of the conductive coating on the insulating sheets, desired indicia or symbols are etched in the conductive coating as shown in FIGURE 4. In other words, a suitable acid or other etching solution is utilized to remove the conductive coating from an area 26 which outlines a symbol such as the numeral 1 shown in FIG- URE 4. A narrow path 27 is left leading to the edge of the sheet upon which the numeral is etched. One of the sheets 28 is not etched.

Instead of depositing a conductive coating on a thin glass insulator, other means may result in a barrier suitable for use in this invention. For example, aluminum foil may be perforated, then'anodized to make it insulating, and a conductive coating in a desired pattern may be deposited thereon.

Following the production of a desired number of sheets each having different symbols etched thereon, the insulating sheets are stacked together in such a way that the perforations 36 are all aligned so as to form straight passageways 40, 42, 44 and 46 through the stack of sheets which form the barrier. An end sheet 28 in the stack, on the side of the stack facing the source of electrons, has no symbol etched thereon, but is left with a complete conducting surface. The sheets may be held together by any desired means, as for example, by an insulating cement.

All of the paths 27 on the sheets which lead to the etched numerals or other indicia are then connected to a single conductor 30, and all of the background areas 32 constituting the remainder of each conductive layer of the barrier are separately and individually connected by means of conductors 31 to a switching mechanism 34. Such a switching mechanism is well known in the art and needs no further description here. Suffice it to say that the mechanism is such as to provide a choice of potentials to each of the separate conductors 31 and the backgrounds 32.

All of the numerals or other symbols or characters which are etched in the conductive layers, and the conductive coating on sheet 28, are connected to a potential which is positive with respect to the potential of the electron beam. The potential may actually be a negative potential, but it must be less negative than the potential of the electron beam, and therefore it is indicated on the drawing as being positive. The background portions of the conductive layers, however, may selectively be connected to either of a potential which is positive with respect to the potential of the electron beam or one which is negative with respect to the potential of the electron beam, and is therefore indicated on the drawing as being negative. Thus, the negative sign means that this biasing is to a greater negative potential than that of the electron beam.

As assembled in the tube, the sheet 28, having the continuous positively biased coating thereon, is faced toward the electron gun. Then in operation, the electron beam is drawn toward the barrier and electrons flow into the passageways 40, 42, 44 and 46 formed by aligned perforations in the disks.

To display a given symbol on the fluorescent target, one background in the stack of disks in the barrier will be biased negative while all the rest are biased positive. It will therefore be seen, upon observing FIGURE 5 of the through the apertures.

It will be apparent that negatively biasing a single background area in the stack of disks in the barrier prevents the flow of electrons through the background area, and therefore prevents the flow of electrons through, for example, passages 42, 44 and 46 as shown in FIGURE 5. In other words the negative voltage applied is sufficient to repulse the flow of electrons through any passageway which traverses a conductor layer which has the more negative potential applied to it.

It will thus be seen that when a single background layer is biased negative, and all other conducting areas are biased positive, the flow of electrons through the barrier will be in a pattern identical to the shape of the symbol on the conductive layer which has the negatively biased background. Thus, the only electrons which reach the screen 16 are those passing through that symbol, and are in the pattern of the desired symbol.

It will therefore be apparent that when it is desired to display any particular symbol, indicia or character on the face plate of the tube, it is only necessary that the switching mechanism be actuated as required to apply the more negative potential to the background of the conductive layer containing that particular desired symbol. Of course, the symbol displayed can be changed as quickly as the switching mechanism can operate from one symbol to the next.

Similarly, the color of the display symbol is also as readily changed. This is accomplished by merely switching conductors 17 and 19 to positive or negative as is required. If it is desired to display, for example, a red numeral on the fluorescent target, one conductive group of strips 18 or 20 on the screen 16 is biased negative and the other biased positive with respect to the electron beam. Thus, the potential of the strips biased negative will repulse the electrons flowing through the barrier and the potential of the strips biased positive will attract these electrons, so as to cause the flowing electrons to converge into the apertures in the positively biased strips and pass on through to impinge upon the red phosphor on the fluorescent target, thereby causing a red image to appear on the target.

It will also be apparent that all of the symbols or characters displayed appear at the face plate itself and not at some point deeper within the tube. This is often of great importance since otherwise it might be necessary for one viewing the display to be nearly directly in front of the tubr in order to read the symbols displayed.

Although the invention has been described in terms of use of two colors, namely red and green, other colors as well as white might also be included. For example, three colors might be alternated instead of just red and green, and two or more colors might be used in combination in order to obtain still other colors. Also, the dilferent phosphors may well be arranged in other arrangements which give better resolution characteristics for viewing of the displayed symbols.

Futhermore, it is apparent that if only a single color of symbol is desired, the screen 16 may be omitted, and a single phosphor may be used on the face plate.

As hereinbefore stated, known features may be selected for inclusion in the tube of the type described herein, but it has not been attempted to describe such known features, but only point out a specific embodiment of so much of the disclosure as is necessary to describe the invention in terms understandable to those skilled in the art. Various improvements and modifications thereof will become apparent to those skilled in the art, and, therefore, the invention is not considered to be limited to the specific embodimentsshown and described herein, but only as set forth and included within the scope of the appended claims.

I claim:

1. A symbol displaying electron discharge tube comprising:

an evacuated envelope,

a luminescent display surface in said envelope,

said luminescent display surface comprising a plurality of phosphors of different color response each substantially uniformly distributed in incremental portions,

an electron gun projecting an electron beam toward said surface,

means to collimate the electrons of said electron beam into substantially parallel paths,

a barrier comprising a plurality of perforated insulating sheets laminated together with aligned apertures positioned in the path of the flood of electrons,

a conductive coating formed in the shape of a desired symbol on each sheet,

a conductive coating forming a background on each sheet electrically disconnected from said symbol coating,

each conductive coating extending into underlying perforations,

means for applying a potential positive with respect to the beam potential to all of said symbols,

means for selectively applying a potential negative with respect to the beam potential to a desired one of said backgrounds,

means for applying a potential positive with respect to the beam potential to the remainder of said backgrounds,

a screen between said surface and said barrier divided into a plurality of conductors, equal in number to the number of phosphors, each conductor being aligned with one of said phosphors,

and means for selectively connecting each conductor to a potential positive or negative with respect to the potential of the beam coming from the barrier.

2. A display-producing device comprising:

a luminescent surface comprising a plurality of phosphors of different color response each substantially uniformly distributed in incremental portions,

means for directing an electron beam toward said surface,

a barrier in front of said surface,

said barrier comprising a plurality of separate conducting layers having aligned perforations through which electrons may pass,

each conducting layer being configured to form a symbol and a separate background,

means for applying a potential to all of said symbols which is positive with respect to the beam potential,

means for selectively applying a potential to a desired one of said backgrounds which is negative with respect to the beam potential,

means for applying a potential to the remainder of said backgrounds which is positive with respect to the beam potential,

a screen between said surface and said barrier,

said screen being insulatingly divided into a plurality of separate conductors, each of which corresponds in configuration to the distribution of one of the phosphors of the luminescent surface,

and means for selectively connecting each screen conductor to a potential positive or negative with respect to the potential coming from the barrier,

whereby electrons may pass through all of the perforations in the barrier except those surrounded by conductors having a more negative potential and through the screen where connected to a positive potential, thereby impinging on the desired phosphor 7 on the luminescent screen in a pattern identical to the form of the symbol on the conducting layer where the background has a more negative potential.

3. A symbol displaying electron discharge tube comprising:

an evacuated envelope,

a fluorescent screen,

an electron gun projecting an electron beam toward said screen,

means to collimate the electrons of said electron beam into substantially parallel paths so as to substantially uniformly flood said screen,

a plurality of perforated insulating sheets laminated together with aligned apertures positioned adjacent said screen in the path of the flood of electrons,

a conductive coating formed in the shape of a desired symbol on each sheet,

a conductive coating forming a background on each sheet electrically disconnected from said symbol coating,

each conductive coating extending into underlying perforations,

means for applying a potential positive with respect to the beam potential to all of said symbols,

means for selectively applying a potential negative with respect to the beam potential to a desired one of said backgrounds,

and means for applying a potential positive with respect to the beam potential to the remainder of said backgrounds.

4. A symbol displaying electron discharge tube as defined by claim 3 wherein:

said sheets are each less than about 0.003 inch thick, and have at least about 30 perforations to the inch, and the conductive coating extending into the perforations from one face of the sheet does not extend all the way to the other face.

5. A symbol displaying electron discharge tube comprising:

a luminescent screen,

means providing an electron beam directed toward said screen,

a barrier in front of said screen comprising alternate conducting and nonconducting layers,

a plurality of perforations through said barrier through while electrons may pass to impinge on said screen,

each conducting layer being configured to form a symbol and a separate background, and

means for selectively applying potentials to said symbols and said backgrounds to prevent passage of electrons through said barrier to said screen except in the pattern of a desired symbol.

6. A display-producing device comprising:

a luminescent screen,

means for directing an electron :beam toward said screen,

a barrier in front of said screen,

said barrier comprising a plurality of separate conducting layers having aligned perforations through which electrons may pass to impinge upon said screen,

each conducting layer being configured to form a symbol and a separate background, and

means for selectively biasing said symbols and said backgrounds to allow passage of electrons through said barrier to said screen only as required to energize said screen to display a desired symbol.

7. A display-producing device as defined by claim 6 wherein:

said conducting layers are separated by insulating layers, and

the conductors extend partly through the perforations in the insulating layers.

8. A display-producing device as defined by claim 6 wherein:

the potentials applied to said backgrounds and said symbols are such as to prevent passage of electrons through said barrier except through perforations in the pattern of a selected symbol to form a lighted area on the screen in that shape of said selected symbol. 9. A display-producing device as defined by claim 8 wherein:

said conducting layers are separated by insulating layers, and the conductors extend partly through the perforations in the insulating layers. 10. A display-producing device as defined by claim 3 wherein:

each conducting layer comprises a conductive coating deposited on a perforated insulating sheet, and each conducting layer comprises a symbol portion and an electrically separate background portion. 11. A display-producing device as defined 'by claim 10 wherein:

the conducting coating extends part way into each perforation. 12. A display-producing device comprising: a luminescent screen, means for directing an electron beam toward said screen, a barrier in front of said screen, a said barrier comprising a plurality of separate conducting layers having aligned perforations through which electrons may pass to impinge upon said screen, each conducting layer being configured to form a symbol and a separate background, and means for applying a potential to all of said symbols which is positive with respect to the beam potential, means for selectively applying a potential to a desired one of said backgrounds which is negative with respect to the beam potential, and means for applying a potential to the remainder of said backgrounds which is positive with respect to the beam potential, whereby electrons may pass through all of the perforations in the barrier except those surrounded by conductors having a more negative potential, thereby impinging on the luminescent screen in a pattern identical to the form of the symbol on the conducting layer where the background has a more negative potential. 13. A display-producing device comprising: an evacuated envelope, a luminescent display surface in said envelope, said luminescent display surface comprising a plural- 'ity of phosphors of different color response, each substantially uniformly distributed in incremental portions, means for directing an electron play surface, a barrier positioned between said means and said display surface, said barrier comprising a plurality of separate conducting layers having aligned perforations through which electrons may pass to impinge upon said display surface, each conducting layer being configured to form a symbol and a separate background, means for selectively biasing said symbols and said backgrounds to allow passage of electrons through said barrier only in the pattern of a desired symbol, and means between said barrier and said display sur- =beam toward said disface adapted to selectively direct the electrons.

passing through the barrier to a selected one of said phosphors.

(References on following page) References Cited UNITED STATES PATENTS 10/1953 Parker BIS-21 X 11/1958 Knlper et a1. 315-21 12/1960 Nixon 31521 10 FOREIGN PATENTS 830,804 3/1960 Great Britain.

RODNEY D. BENNETT, Primary Examiner.

B. L. RIBANDO, Assistant Examiner. 

